Machine-readable codes, such as barcodes, QR codes, visual features or patterns, and watermarks are representations of information in a visual format. Such codes may include data characters and/or overhead characters represented by a particular sequence of bars and/or spaces that may have varying widths. Such codes have widespread applications. For example, machine-readable codes can be used to identify a class of objects or unique items. As a result, these codes are found on a wide variety of objects, such as documents, retail goods, shipping boxes, product parts, company assets, and so on.
There are several types of data readers used for reading machine-readable codes. The most common types of readers are barcode scanners. In some cases, the barcode scanner moves or scans a laser light beam across the barcode. In some cases, the barcode scanners include solid state image circuitry, such as charge coupled devices (CCD) or complementary metal-oxide semiconductor (CMOS) devices, and may be implemented using a one-dimensional or two-dimensional imaging array of photo sensors or pixels to capture an image of the optical code. One-dimensional CCD readers may capture a linear cross-section of the code to produce an analog waveform whose amplitude represents the relative darkness and lightness of the code. Two-dimensional CCD or CMOS readers may capture an entire two-dimensional image.
FIG. 1A and FIG. 1B illustrate a conventional handheld barcode scanner 100a and a fixed barcode scanner 100b, respectively. In some embodiments, the handheld barcode scanner 100a and/or the fixed barcode scanner 100b may be a direct part marking (DPM) barcode scanner capable of reading barcodes that are etched or imprinted directly into a surface of an object 102. As shown, the handheld barcode scanner 100a has a short focal length and is manually placed very close to the object being scanned, while the fixed barcode scanner 100b has a fixed-length or variable focal length, and is fixedly positioned to scan objects with a fixed distance below the scanner 100b. If a variable focal length, the barcode scanner 100b includes a mechanical zoom camera, as further described herein.
One example of the barcode scanner is a conventional direct part marking (DPM) barcode scanner 200, as illustrated in FIG. 2. Conventional DPM barcode scanner 200 is a two-dimensional scanner equipped with optical components, such as cameras and imagers, which are capable of reading barcodes, such as those that are etched or imprinted directly into a surface of materials of items, such as plastic and metal. The conventional DPM barcode scanner 200 may be a hand-held device or a fixed device. A camera system of the conventional DPM barcode scanner 200 may be configured to capture images of the item. It has been observed that an ability to control a depth-of-field 202 (e.g., shorter than a few feet) of the DPM barcode scanner 200 is limited. Typically, the DPM barcode scanner 200 is designed to have a shorter depth-of-field 202 and fails to work for applications that specify a longer depth-of-field (e.g., longer than a few feet).
In order to improve the ability to control the depth-of-field of the conventional DPM barcode scanner 200, for instance, by having the DPM barcode scanner 200 that is able to work for the applications that specify a variable depth-of-field due to having to scan objects that are both near and far away, a camera system having a zoom function is essential within the DPM barcode scanner 200. A conventional technique to facilitate an ability of the zoom function within the camera system of the DPM barcode scanner 200 typically involves a use of two motor assemblies, such as a starter motor to provide an electric effect and enable the zoom function within the camera system. However, the use of motor-based camera system within the DPM barcode scanner 200 to enable a zoom function has several disadvantages. First, a presence of two large size motors within the camera system of the DPM barcode scanner 200 increases the overall size and weight of the DPM barcode scanner 200. Second, a presence of two small sized motors within the camera system of the DPM barcode scanner 200 makes the DPM barcode scanner 200 unsuitable for several industrial applications. As an example, if the DPM barcode scanner 200 is operated at a very low temperature, such as minus 30 degree Celsius, or a very high temperature, such as plus 70 degree Celsius, small sized motors within the camera system are typically based on a piezoelectric effect, and the piezoelectric effect eventually makes the DPM barcode scanner 200 resistant to operate in both high and low temperatures. Third, a motor-based camera system in the DPM barcode scanner 200 have movable parts, which is problematic because such a camera system of the DPM barcode scanner 200 cannot resist a drop of more than two meters as necessitated for industrial uses.
As understood, the above-described conventional camera-based DPM barcode scanner that are currently available have lower depth-of-field. In order to improve the ability to control the depth-of-field of a DPM barcode scanner, a camera system having a zoom function is essential within the DPM barcode scanner. However, the use of conventional zoom function enabled camera systems within the DPM barcode scanner leads to an increase in the overall size and weight of the DPM barcode scanner, includes problematic movable elements, and increases overall high cost of production due to the requirement of additional components, such as a motor. Therefore, there is a need for an improved camera system to improve an ability to control a depth-of-field eliminate moving parts, and reduce size and weight of a barcode scanner, used to read barcodes on a part or item, as well as provide improved optics for other imaging systems.